The present disclosure relates to semiconductor memory devices, and, more particularly, to nonvolatile memory devices.
Semiconductor memory devices are memory devices that can store data and read stored data when necessary. Semiconductor memory devices are typically classified into volatile memory devices and nonvolatile memory devices.
Volatile memory devices lose their stored data when a power supply is interrupted. Volatile memory devices include static random access memory (SRAM), dynamic random access memory (DRAM) and synchronous dynamic random access memory (SDRAM). Nonvolatile memory devices retain their stored data even when a power supply is interrupted. Nonvolatile memory devices include read only memory (ROM), programmable read only memory (PROM), erasable programmable read only memory (EPROM), electrically eraseable programmable random access memory (EEPROM), flash memory devices, phase-change random access memory (PRAM), magnetoresistive random access memory (MRAM) and ferroelectric random access memory (FRAM). Flash memory devices may be classified into a NOR-type and a NAND-type.